Use of derivatives of N-phenl-3,4,5,6-tetrahydrophthalimide for the desiccation and abscission of plant organs

ABSTRACT

Derivatives of N-phenyl-3,4,5,6-tetrahydrophthalimide of formulae I and/or II                    
     where A, R, E n , Y, and R 16  have the meanings stated in the description, which compounds are used for the dessication and abscission of plant organs.

This application is a continuation of patent application Ser. No. 08/294,784, filed on Aug. 8, 1994, now abandoned, which is a continuation of patent application Ser. No. 08,115,595, filed on Sep. 3, 1993, now abandoned, which is a reissue application of U.S. Pat. No. 5,045,105.

The present invention relates to the use of derivatives of N-phenyl-3,4,5,6-tetrahyrophthalimide of the general formulae I and/or II

where

R is hydrogen, fluorine or chlorine,

A is hydrogen, C₁-C₄cyanoalkyl or a group I-1 to I-11

R¹ is hydrogen, chlorine, bromine cyano or C₁-C₆-alkyl,

R² is hydrogen, C₁-C₈-alkyl, C₁-C₈-alkenyl C₂ -C ₈₋ alkenyl, C₂-C₄-alkynyl, C₁-C₄-alkoxy-C₁-C₄-alkyl, C₁-C₄-alkylthio-C₁-C₄-alkyl, phenyl-C₁-C₃-alkyl or, where X is NR⁸where Q is NR⁸, also C₁-C₄-hydroxy-alkyl, C₁-C₄-alkoxy, C₂-C₄-alkenyloxy, phenyl, phenyl substituted by halogen, C₁-C₄-alkyl or -alkoxy, C₁-C₄-haloalkyl or -haloalkoxy,

R³ is hydrogen, C₁-C₄-alkyl, C₁-C₄-hydroxyalkyl, C₁-C₄-haloalkyl, C₁-C₅-cyanoalkyl, C₁-C₄-mercaptoalkyl, C₁-C₄-alkoxyalkyl, C₁-C₄-alkylthioalkyl, C₁-C₄-alkylcarbonyloxy-C₁-C₄-alkyl or C₁-C₄-alkoxycarbonyl-C₁-C₄-alkylthioalkyl,

R⁴, R⁵ and R⁶ are each hydrogen or C₁-C₃-alkyl,

E is oxygen or methylene,

X is oxygen or sulfur,

Q is oxygen, sulfur or N⁸,

Y is oxygen, sulfur or CHR⁴,

n is 0 or 1,

Z is methylene, methyleneoxymethylene, methylenethiomethylene or ethenylene, R⁷ is hydrogen, C₁-C₆-alkyl, C₁-C₆-alkoxyalkyl, C₁-C₆-alkylthioalkyl or C₅- or C₆-cycloalkyl,

R⁸ is C₁-C₈-alkyl, C₃-,or C₄-alkenyl, C₃- or C₄-alkynyl or C₁-C₆-alkoxyalkyl,

R⁹ is hydrogen, chlorine, bromine, cyano, C-C₄-alkyl, C₃- or C₄-alkenyl, C₃- or C₄-alkynyl, C₁-C₆-alkoxyalkyl, C₁-C₆-alkylthioalkyl or cyclohexylmethyl,

R¹⁰ is hydrogen, halogen, cyano, C₁-C₄-alkyl, C₁-C₃-alkoxycarbonyl or C₁-C₄-alkoxycarbonyl, or R⁹ and

R¹⁰ together form a C₄- or C₅-alkylene or C₄- or C₅-oxoalkylene group,

R¹¹ is C₁-C₆-alkyl, C₃- or C₄-alkenyl, C₃- or C₄-alkynyl or a group

 or —CH₂C(CH₃)₂COOR²,

R¹² is hydrogen or cyano,

R¹³ is hydrogen or C₁-C₄-alkoxycarbonyl,

R¹⁴ is C₁-C₄-alkyl, C₃- or C₄-alkenyl, C₃- or C₄-alkynyl, C₁-C₄-alkylcarbonyl, C₁-C₄-alkoxycarbonyl-C₁-C₄-alkyl, tetrahydrofurfuryl, dihydropyranylmethyl, dihydrothiopyranylmethyl, tetrahydropyranylmethyl or tetrahydrothiopyranylmethyl,

R¹⁵ is hydrogen, C₁-C₄-alkyl, C₃- or C₄-alkynyl, C₁-C₄-alkoxycarbonyl -C₁-C₄-alkyl or —N═C(CH₃)₂ and

R₁₆ is hydrogen; C₁-C₄-alkyl, C₃- or C₄-alkenyl, C₃- or C₄-alkynyl, unsubstituted benzyl or benzyl which is, monosubstituted to trisubstituted by halogen or C₁-C₄-alkyl, tetrahydrofurfuryl, dihydropyranylmethyl, dihydrothiopyranylmethyl, tetrahydropyranylmethyl or tetrahydrothiopyranylmethyl,

for the desiccation and abscission of plant organs.

The present invention furthermore relates to a method for the desiccation and abscission of plant organs, in particular of the leaves, by means of the above-mentioned compounds I and II.

EP-A 207 894 discloses that specially substituted N-phenyl-3,4,5,6-tetrahydrophthalimides have selected herbicidal properties as well as a plant growth-regulating action. An example indicates the desiccant and defoliant action in cotton plants without specifying the active ingredients. The application rates are 0.6 and 1.2 kg/ha. Evidently no good results were obtained with 0.3 kg/ha.

The use of tetrahydrophthalimide derivatives as herbicides is described in a number of publications, for example in DE-A-36 03 789, DE-A-36 07 300, DE-A-30 13 162, DE-A-31 09 035, DE-A-35 33 440, EP-A-61 741, EP-A-83 055, EP-A-68 822, EP-A-236 916, GB-A-20 71 100, U.S. Pat. No. 3,878,224, JP 59/155 358 and JP 61/027 962. These publications do not disclose the use of the compounds as abscission agents for the controlled induction of the dropping of leaves, blossoms of fruit in crops, such as cotton, citrus fruit, olives, pomes and drupes, and their use as desiccants for drying out the visible parts in crops, for example potato, rape, sunflower and soybean.

There is considerable economic interest in both abscission agents and desiccants, for facilitating harvesting. Particularly in intensive cotton cultivation, the use of defoliants is essential for effective use of picking machines or harvesting the bolls. The commercial products used to date do not meet essential requirements in practice, for example rapid and lasting activity even under cooled temperature conditions, low application rates and no environmental pollution (toxicity, odor and flammability).

We have found that the N-phenyl-3,4,5,6-tetrahydrophthalimides defined at the outset have high activity with regard to the abscission and desiccation of plant organs. Their use has considerable advantages compared with known agents:

a) Their action is optimum even at low application rates of about 60-250 g/ha,

b) Their effect is much more complete at a comparable application rate and

c) Their action is much more reliable even at low temperatures.

In addition to their excellent action as defoliants, the compounds I and/or II have very good activity when they are used as desiccants for drying out the visible parts of crop plants, for example potatoes, sunflower, soybean and rape, in order to facilitate the harvesting process. Furthermore, they result in uniform ripening of the fruit to be harvested.

The compounds which are particularly preferred because of their activity are N-phenyl-3,4,5,6-tetrahydrophthalimides of the structure I, where R is fluorine or, in particular, hydrogen.

Preferred radicals A are the following groups:

where Q is oxygen, R¹ is H, Cl, Br, CN or C₁-C₆-alkyl, in particular C₁-C₄-alkyl, and R² is H, C₁-C₈-alkyl, in particular C₁-C₄-alkyl, such as methyl, ethyl, propyl, isopropyl, n-butyl or isobutyl, C₁-C₈-alkenyl C₂ -C ₈-alkenyl, in particular C₁-C ₄-alkenyl , C₂ -C ₄-alkenyl, C₃- or C₄alkynyl C₄ alkynyl, C ₁-C₈-C₄-alkylthio-C₁-C₄-alkyl , C₁ -C ₄-alkylthio-C ₁ -C ₄-alkyl, C₁-C₁₇-aralkyl, for example phenylalkyl, such as benzyl or 2-phenylethyl, or C₃-C₆-cycloalkyl, in particular C₅- or C₆-cycloalkyl, such as cyclopentyl or cyclohexyl,

where X is O or S, n is 0 or 1, R³ is H or C₁-C₄-alkyl as stated for R₂, which may be substituted by hydroxyl, halogen, such as fluorine, chlorine or bromine, cyano, mercapto, C₁-C₄-alkoxy, C₁-C₄-alkylthio, C₁-C₄-alkyl-carbonyloxy or C₁-C₄-alkoxycarbonyl-C₁-C₄-alkylthio, and R⁴ is hydrogen or C₁-C₃-alkyl,

OR¹⁴  ( I-10

where R¹⁴ is, in particular, tetrahydrofurfuryl, dihydropyranylmethyl, dihydrothiopyranylmethyl, tetrahydropyranylmethyl or tetrahydrothiopyranylmethyl.

The N-substituted tetrahydrophthalimides I are obtainable from 3,4,5,6-tetrahydrophthalic anhydride and appropriately substituted aniline derivatives, which can be prepared by reduction of the corresponding nitro compounds. As a rule, the reaction is carried out in an inert solvent at from 20° to 200° C., preferably from 40° to 50° C. Examples of suitable solvents are lower alkanecarboxylic acids, such as glacial acetic acid or propionic acid, or aprotic solvents, such as toluene or xylene, in the presence of acidic catalysts, for example aromatic sulfonic acids.

Cyanoalkyl-substituted N-phenyltetrahydrophthalimides are described in EP-A 68 822.

N-phenyltetrahydrophthalimides in which A is a group I-1 are disclosed in DE-A 36 03 789 (EP-A 240 659) or DE-A 37 24 399 (EP-A-300 387). They can also be prepared by reacting an aldehyde of the formula IV

with a phosphorane of the formula V

where Ar is unsubstituted or substituted phenyl at from −10° to 100° C. and in the presence of a solvent. The aldehydes of the general formula IV which are used as starting materials are obtainable in a simple manner by the methods described in German Patent Application 3815042.5 (0.Z. 0050/39993). The radical R of these compounds may be hydrogen or fluorine.

The phosphoranes V which are required for the preparation of the tetrahydrophthalimides and which are also referred to as phosphorylides are obtainable by methods known from the literature (for example Houben-Weyl, Methoden der Organischen Chemie, Vol. E1, pages 636-639, Georg-Thieme Verlag, Stuttgart 1982).

The reaction of the starting compounds IV and V is in general advantageously carried out in the presence of a solvent. Suitable solvents are all solvents conventionally used for carrying out Wittig reactions, for example halogenated solvents, such as chloroform, or ethers, such as tetrahydrofuran, dioxane or ethylene glycol dimethyl ether. Preferred solvents are alcohols, in particular C₁-C₄-alcohols, such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol or tertbutanol. The solvents can also be used in the form of solvent mixtures but as a rule the pure solvents are preferably employed. If alcohols are used as solvents, it is generally advantageous to use as a solvent that alcohol which corresponds to the alcohol component of the ester group in I and V.

Of course, the optimum reaction temperature depends on the particular starting compounds IV and V to be reacted and on the solvent used. In general, however, the reaction is carried out at from −10° to 100° C., preferably from −10° to 60° C., particularly advantageously from 10° to 40° C.

The starting compounds IV and V can be reacted with one another in stoichiometric amounts. However, it may prove advantageous if one of the two reactants, IV or V, is used in the reaction in a molar excess of from 10 to 20%.

N-phenyltetrahydrophthalimides in which the Group A is I-2 or I-3 are described in German Applications P 37 41 272.8 and P 37 41 273.6. Compounds in which A is I-4 or I-5 are disclosed in DE-A-36 03 789 (EP-A-240 659). N-phenyltetrahydrophthalimides in which A is I-6 and I-7 are described in German Applications P 37 41 272.8 and P 38 19 464.3. Compounds I in which A is I-8 and I-9 are disclosed in DE-A-37 24 395 (EP-A-300 398) and 36 07 300 (EP-A-236 916). Compounds I in which A is I-10 are described in German Application P 37 36 297.6. Compounds I in which A is I-11 are disclosed in DE-A-31 09 035 and 35 33 440 and in GB-A-20 71 100.

N-aryltetrahydrophthalimide compounds of the structure II can be obtained by reacting a correspondingly substituted amine III

with an N-alkylating compound Z-R¹⁶, where Z is an acid radical which initiates N-alkylation, and reacting the resulting amine in a conventional manner with tetrahydrophthalic anhydride. It is also possible first to carry out the reaction of III with tetrahydrophthalic anhydride and then to effect N-alkylation. Preferred alkylating agents are halogen compounds, tosylates or mesylates of the radicals to be introduced. The preparation of compounds of the structure II is described in, for example, German Application P 38 07 295.5.

The active ingredients I and/or II may be used, for example, in the form of directly sprayable solutions, powders, suspensions, including concentrated aqueous, oily or other suspensions or dispersions, emulsions, oil dispersions, pastes, dusting agents, broadcasting agents or granules, by spraying, atomizing, dusting, broadcasting or pouring. The application forms depend entirely on the intended uses; they should in any case ensure very fine distribution of the novel active ingredients.

Mineral oil fractions having a medium to high boiling point, such as kerosine or diesel oil, and coal tar oils and vegetable or animal oils, aliphatic, cyclic and aromatic hydrocarbons, e.g. benzene, toluene, xylene, paraffin, tetrahydronaphthalene, alkylated naphthalenes or their derivatives, for example methanol, ethanol, propanol. butanol, chloroform, carbon tetrachloride, cyclohexanol, cyclohexanone, chlorobenzene, isophorone, highly polar solvents, e.g. dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone or water, are suitable for the preparation of directly sprayable solutions, emulsions, pastes or oil dispersions.

Aqueous application forms can be prepared from emulsion concentrates, pastes or wettable powders (spray powders, oil dispersions) by adding water. To prepare emulsions, pastes or oil dispersions, the substances as such may be dissolved in an oil or solvent and homogenized in water by means of wetting agents, adhesives, dispersants or emulsifiers. However, it is also possible to prepare concentrates which consist of active substance, wetting agents, adhesives, dispersants or emulsifiers and possibly solvents or oil and which are suitable for dilution with water.

Suitable surfactants are alkali metal, alkaline earth metal and ammonium salts of ligninsulfonic acid, naphthalenesulfonic acid, phenolsulfonic acid, alkylarylsulfonates, alkylsulfates, alkylsulfonates, alkali metal and alkaline earth metal salts of dibutylnaphthalenesulfonic acid, lauryl ether sulfate, fatty alcohol sulfates, alkali metal and alkaline earth metal salts of fatty acids, salts of sulfated hexadecanols, heptadecanols, octadecanols, salts of sulfated fatty alcohol glycol ethers, condensates of sulfonated naphthalene and naphthalene derivatives with formaldehyde, condensates of naphthalene or of naphthalenesulfonic acid with phenol and formaldehyde, polyoxyethylene octylphenol ether, ethoxylated isooctylphenol, octylphenol, nonylphenol, alkylphenol polyglycol ethers, tributylphenyl polyglycol ether, alkylaryl polyether alcohols, isotridecyl alcohol, fatty alcohol ethylene oxide condensates, ethoxylated castor oil, polyoxyethylene alkyl ethers, ethoxylated polyoxypropylene, lauryl alcohol polyglycol ether acetal, sorbitol esters, ligninsulfite waste liquors and methylcellulose.

Powder, broadcasting, coated, impregnated and homogeneous granules can be prepared by binding the active ingredients to solid carriers. Solid carriers are mineral earths, such as silica gel, silicas, silicates talc, kaolin, attaclay, limestone, lime, chalk, bole, loess, clay, dolomite, kieselguhr, calcium sulfate, magnesium sulfate, magnesium oxide, milled plastics, fertilizers, e.g. ammonium sulfate, ammonium phosphate, ammonium nitrate, ureas and vegetable products, such as cereal meal, ground bark, woodmeal, nutshell meal and cellulose powder, and other solid carriers.

The formulations contain from 0.1 to 95, preferably from 0.5 to 90% by weight of active ingredient.

Examples of formulations are:

I. 90 parts by weight of the compound according to Example 1.1 are mixed with 10 parts by weight of N-methyl-α-pyrrolidone to give a solution which is suitable for use in the form of very small drops.

II. 20 parts by weight of the compound of Example 1.17 are dissolved in a mixture which consists of 80 parts by weight of xylene, 10 parts by weight of the adduct from 8 to 10 moles of ethylene oxide with 1 mole of oleic acid N-monoethanolamide, 5 parts by weight of the calcium salt of dodecylbenzenesulfonic acid and 5 parts by weight of the adduct of 40 moles of ethylene oxide with 1 mole of castor oil. By pouring the solution into 100,000 parts by weight of water and finely dispersing it, an aqueous dispersion which contains 0.02% by weight of the active ingredient is obtained.

III. 20 parts by weight of compound No. 1.17 are dissolved in a mixture which consists of 40 parts by weight of cyclohexanone, 30 parts by weight of isobutanol, 20 parts by weight of the adduct of 7 moles of ethylene oxide with 1 mole of isooctylphenol and 10 parts by weight of the adduct of 40 moles of ethylene oxide and 1 mole of castor oil. By pouring the solution into 100,000 parts by weight of water and finely dispersing it, an aqueous dispersion which contains 0.02% by weight of the active ingredient is obtained.

IV. 20 parts by weight of compound No. 4.1 are dissolved in a mixture which consists of 25 parts by weight of cyclohexanol, 65 parts by weight of a mineral oil fraction boiling within a range from 210° to 280° C. and 10 parts by weight of the adduct of 40 moles of ethylene oxide with 1 mole of castor oil. By pouring the solution into 100,000 parts by weight of water and finely dispersing it, an aqueous dispersion which contains 0.02% by weight of the active ingredient is obtained.

V. 20 parts by weight of compound No. 1.26 are mixed thoroughly with 3 parts by weight of the sodium salt of diisobutylnaphthalene-α-sulfonic acid, 17 parts by weight of the sodium salt of a ligninsulfonic acid from a sulfite waste liquor and 60 parts by weight of silica gel powder, and the mixture is milled in a hammer mill. By finely distributing the mixture in 20,000 parts by weight of water, a spray liquor which contains 0.1% by weight of the active ingredient is obtained.

VI. 30 parts by weight of compound No. 1.26 are mixed with 97 parts by weight of finely divided kaolin. A dusting agent which contains 3% by weight of the active ingredient is obtained in this manner.

VII. 30 parts by weight of compound No. 1.17 are thoroughly mixed with a mixture of 92 parts by weight of silica gel powder and 8 parts by weight of paraffin oil, which has been sprayed on the surface of this silica gel. A formulation of the active ingredient having good adhesion is obtained in this manner.

VIII. 20 parts by weight of compound No. 1.17 are mixed thoroughly with 2 parts of the calcium salt of dodecylbenzenesulfonic acid, 8 parts of a fatty alcohol polyglycol ether, 2 parts of the sodium salt of a phenolsulfonic acid/urea/formaldehyde condensate and 68 parts of a paraffinic mineral oil. A stable oily dispersion is obtained.

The action and the rate of action can be promoted, for example, by means of additives which increase the action, such as organic solvents, wetting agents and oils. This allows the application rate of the actual active ingredient to be reduced.

The application rate of the individual active ingredients is varied according to the desired effect, plant species, stage of development of the plants to be treated and agents to be used.

The agents are supplied to the plants mainly by spraying the foliage. Application may be effected, for example using water as a carrier, by conventional spraying techniques using amounts of spray liquor of about 100-1,000 l/ha. The agents can be applied both by the low volume and ultra low volume methods and in the form of microgranules.

The novel agents can be used in application rates of from 0.001 to 5, preferably from 0.01 to 3, in particular from 0.01 to 0.6, kg/ha.

The agents can be applied either alone or as a mixture with other agents or with other active ingredients. If necessary, other defoliants, desiccants, crop protection agents or pesticides can be added, depending on the desired purpose.

It has also been found that mixtures of the novel agents with, for example, active ingredients (A)-(C) stated below lead to further promotion of the desiccant and defoliant effect and help to achieve better control of the undesirable resprouting of plants after desiccation or defoliation (particularly in cotton):

(A) Herbicidal active ingredients from the group consisting of

a. chloroacetanilides, for example 2-chloro-N-(2,6-dimethylphenyl)-N-(1H-pyrazol-1-ylmethyl)-acetamide (common name: metazachlor) described in German Laid-Open Application DOS 2,648,008,

b. substituted quinoline-8-carboxylic acids, for example 3,7-dichloroquinoline-8-carboxylic acid (common name: quinchlorac) described in EP-A-60 429 and 3-methyl-7-chloroquinoline-8-carboxylic acid (common name: quinmerac) described in EP-A-104 389,

c. cyclohexenone derivatives, for example 2-(1-ethoxyimino)-butyl]-5-[2-(ethylthio)-propyl]-3-hydroxy-2-cyclohexenone (common name: sethoxydim) described in German Laid-Open Application DOS 2,822,304 and 2-[1-(ethoximino)-butyl]-3-hydroxy-5-(2H-tetrahydrothiopyran-3-yl)-2-cyclohexen-1-one (common name: cycloxydim) described in German Laid-Open Application DOS 3,121,355,

d. phenoxyalkanecarboxylic acids, for example (4-chloro-2-methylphenoxy)-acetic acid,

e. 3-(isopropyl)-1H-2,1,3-benzothiadiazin-4-(3H)-one 2,2-dioxide, described in German Laid-Open Application DOS 1,542,836 (Bentazon®),

f. dinitroanilines, for example N-(1-ethylpropyl-3,4-dimethyl-2,6-dinitroaniline described in German Laid-Open Application DOS 2,241,408,

g. imidazolinones, for example 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol -2-yl]-3-quinolinecarboxylic acid (Scepter®, common name: imazaquin); 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-nicotinic acid combined with iso-propylamine in a ratio of 1:1 (Arsenal®, common name: imazapyr); 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl) -5-ethyl-3-pyridinecarboxylic acid (Pursuit®, common name: imazethapyr); methyl 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-p-toluate combined with methyl 6-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-m-toluate (Assert®, common name: imazamethabenz) and imazamethapyr (common name; trade mark: Cadre®), and

h. sulfonylurea derivatives, for example the compounds listed in Tables i and ii below and 1-(4,6-dimethoxypyrimidin-2-yl)-3-(ethylsulfonyl)-2-pyridylsulfonyl)-urea, known as DPX-E 9636.

TABLE i Phenylsulfonylureas

R^(1′) R^(2′) R^(3′) R^(4′) Z′ n disclosed in Cl H CH₃ OCH₃ N 0 D3-A 27 15 786 COOCH₃ H CH₃ OCH₃ N 0 EP-A 7687 COOCH₃ CH₃ CH₃ OCH₃ N 0 EP-A 202 830 OCH₂CH₂Cl H CH₃ OCH₃ N 0 EP-A 44 808 OCH₂CH₂OCH₃ H OCH₃ OCH₃ N 0 EP-A 44 807 COOCH₃ H NHCH₃ OC₂H₅ N 0 EP-A 136 061 COOCH₃ H OCH₃ OCH₃ CH 1 EP-A 51 466 COOCH₃ H CH₃ CH₃ CH 0 EP-A 7687 COOC₂H₅ H Cl OCH₃ CH 0 US-A 4 547 215 COOCH₃ H OCHF₂ OCHF₂ CH 0 EP-A 84 020

TABLE ii Hetarylsulfonylureas

A′ R^(3′) R^(4′) Z′ disclosed in

CH₃ OCH₃ N EP-A 30 142

OCH₃ OCH₃ CH EP-A 237 292 EP-A 232 067

OCH₃ OCH₃ CH JP 59-219 281 of 20.04.83 CA 102, 220 905

The commercial products listed in Tables i and ii are known, for example, under the trade names Glean®, Ally®, Express®, Logran®, Setoff®, Muster®, Londax®, Oust®, Classic®, Beacon®, Harmony®or Remedy®.

i. Diphenyl ether derivatives, such as 5-[2-chloro-4-(trifluoromethyl)-phenoxy]-2-nitrobenzoic acid described in DE-A-23 11 638 and EP-A-40 898 and its salts (acifluorfen) and ethoxycarbonylmethyl 5-[2-chloro-4-(trifluoromethyl)-phenoxy]-2-nitrobenzoate (fluoroglycofen) and the diphenyl ether 1-(carboethoxy)-ethyl 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoate (common name: lactofen, Cobra®, 2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4trifluoromethylbenzene (common name: oxyfluorfen) and 5-(2-chloro-4-trifluoromethyl)-phenoxy)-N-methylsulfonyl)-2-nitrobenzamide (common name: fomesafen, Flex®, EP-A-3416).

(B) Defoliants and desiccants as mentioned, for example, in G. W. Cathey (1986), Physiology of defiolation in cotton production, in Cotton Physiology (J. R. Mauney, J. McD. Stewart, eds.) The Cotton Foundation reference book series, No. 1, Chapter 14, 143-153, in Morgan, P. W. (1985) Chemical manipulation of abscission and desiccation. In Agricultural Chemicals of the Future (J. L. Hilton, ed.) BARC Symposium 8, 61-74. Rowman & Allanheld, Totowa, in R. Krämer (1989) Erstellung leistungsfähiger Kernobstjungpflanzen, thesis at the Faculty of Agriculture of the University of Bonn, and in H. Bergmann, D. Martin (1989), Chemical manipulation of desiccation and defoliation and essential aspects for the application and development of new chemical compounds in the future, in Chemistry of Plant Protection 2 (G. Haug, H. Hoffmann, eds.) 197-246, Springer-Verlag Berlin, Heidelberg.

a. Urea derivatives, for example N-phenyl-N′-1,2,3-thiadiazol-5-ylurea disclosed in German Laid-Open Application DOS 2,506,690, N-phenyt-N′-1.3.4-thiadiazol-2-ylurea described in German Laid-Open Application DOS 3,612,830 or N-phenyl-N′-2-chloropyrid-3-ylurea described in German Laid-Open Application DOS 2,843,722 or the above-mentioned 3-(3-chloro-4-methoxyphenyl)-1,1-dimethylurea (common name: metoxuron),

b. (2-chloroethyl)-phosphonic acid (Ethrel®),

c. S,S,S-tributyl phosphorotrithioate and S,S,S-tributyl phosphorotrithioite,

d. 2,3-dihydro-5,6-dimethyl-1,4-dithiin 1,1,4,4tetraoxide (Harvade®),

e. salts of N-(phosphonomethyl)-glycine, such as the isopropylammonium salt (Roundup®),

f. ammonium DL-homoalanin-4-yl-(methyl)-phosphinate (ammonium glufosinate),

g. magnesium chlorate and sodium chlorate,

h. ammonium sulfate and nitrate,

i. hydrogen cyanamide, calcium cyanamide,

j. potassium iodide,

k. Cu ethylenediaminetetraacetate and Fe ethylenediaminetetraacetate,

l. arsenic acid and its derivatives, such as hydroxydimethylarsine oxide (common name: dimethylarsenic acid),

m. 1,2-dihydropyridazine-3,6-dione,

n. 7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid (common name: endothall),

o. 6,7-dihydrodipyridol (1,2-α:2′,1′-c)pyridinium ion as dibromide monohydrate salt (common name: diquat) and 1,1′-dimethyl-4,4′-bipyridinium ion as dichloride or dimethylsulfate salt (common name: paraquat),

p. 3,5-dibromo- or diiodo-4-hydroxybenzonitrile (common name: bromoxynil),

q. substituted dinitrophenols, such as 2-sec-butyl-4,6-dinitrophenol (common name: dinoseb),

r. triazine derivatives, such as 2-ethylamino-4-isopropylamino-6-methylthio-1,3,5-triazine (common name: ametryne),

s. triazole derivatives, such as 1H-1,2,4-triazol-3-ylamine (common name: amitrol),

t. benzothiazoles, such as 2-n-butylmercaptobenzothiazole (common name: butylcaptax), and

u. di-n-butyl 1-n-butylaminocyclohexyl phosphonate (common name: buminafos).

(C) Growth retardants from the group consisting of

a. quaternary ammonium salts from the group consisting of the

N,N-dimethylazacycloheptanium salts, N,N-dimethylpiperidinium salts,

N,N-dimethylhexahydropyridazinium salts, N,N-dimethyltetrahydropyridazinium salts,

N-methylpyridinium salts,

N,N-dimethylpyrrolidinium salts

and N,N,N-trimethyl-N-2-chloroethylammonium salts,

in particular N-2-chloroethyl-N-trimethylammonium chloride (common name: chlormequat chloride) and N,N-dimethylpiperidinium chloride (common name: mepiquat chloride),

b. pyrimidine compounds, such as those disclosed in U.S. Pat. No. 3,818,009 and in Journal of Plant Growth Regulation 7 : 27, 1988 (for example those having the common name: ancymidol or flurprimidol),

c. pyridine compounds disclosed in DE-A-30 15 025,

d. norbornadiazetines, as described in German Laid-Open Applications DOS 2,615,878 and DOS 2,742,034,

e. growth-regulating triazole compounds as described in European Application 88104320.2, in British Crop Protection Conference - Weeds 1982, Vol. 1, BCPC Publications, Croydon 1982, page 3, in Plant Cell Physiol. , 611, in Pestic. Sci. 19, 153, in J. Agron. Crop Sci. 158, 324 or in J. Plant Growth Regul. 4, 181, for example 1-phenoxy-3-(1H-1,2,4-triazol-1-yl)-4-hydroxy-5,5-dimethylhexane,

f. 2-acyl-3-hydroxycyclohex-2-en-1-ones, as described in, for example, EP-A-126 713 or 123 001,

g. 1-(4-chlorophenoxy)-3,3-dimethyl-1-[1, 2,4-triazol-1-yl]-butan-2-one (common name: triadimefon), N-[2,4-dimethyl-5-[trifluoromethylsulfonylamino]-phenylacetamide (common name: mefluidide), 2-chloro-2′,6′-diethyl-N-[methoxymethyl]-acetanilide (common name: alachlor), S-ethyl dipropylthiocarbamate (common name: EPTC) and succinic acid 2,2-dimethylbydrazide (common name: daminozid).

For example, the following mixing partners can be added:

2-Methyl-6-ethylethoxymethyl-2-chloroacetanilide

2-Methyl-6-N-(methoxy-1-methylethyl)-2-chloroacetanilide

2-6-Dimethyl-N-(1-H-pyrazol-1-ylmethyl)-2-chloroacetanilide

2,6-Diethyl-N-(methoxymethyl)-2-chloroacetanilide

3-Methyl-7-chloroquinoline-8-carboxylic acid (salts, esters)

3,7-Dichloroquinoline-8-carboxylic acid (salts, esters)

2-[(1-Ethoxyimino)-butyl]-5-[2-(ethylthio)-propyl]-3-hydroxy-2-cyclohexan-1-one (salts)

2-[(1-Trans-chloroallyloxyimino)-butyl]-5-[2-(ethylthio)-propyl]-3-hydroxy-2-cyclohexan-1-one (salts)

2-[(1-Trans-chloroallyloximino)-propyl]-5-[2-(ethylthio)-propyl]-3-hydroxy-2-cyclohexan-1-one (salts)

2-[(1-Ethoximino)-butyl)-5-[2-H-tetrahydrothiopyran-3-yl]-3-hydroxy-2-cyclohexan-1-one (salts)

2-[(1-Ethoximino)-propyl]-5-(2,4,6-trimethylphenyl)-3-hydroxy-2-cyclohexan-1-one (salts)

2-Methyl-4-chlorophenoxyacetic acid (salts, esters, amides)

2-[2-Methyl-4-chlorophenoxy]-propionic acid (salts, esters, amides)

4-[2-Methyl-4-chlorophenoxy]-butyric acid (salts, esters, amides)

4-[2,4-Dichlorophenoxy]-butyric acid (salts, esters, amides)

2,4-Dichlorophenoxyacetic acid (salts, esters, amides)

3,5,6-Trichloropyridyl-2-oxyacetic acid (salts, esters, amides)

3-(1-Methylethyl)-1-H-2,1,3-benzothiadiazin-4(3H)-one-2,2-dioxide (salts)

3-(1-Methylethyl)-1-cyano-2,1,3-benzothiadiazin-4-(3H)-one-2,2-dioxide (salts)

N-(1-Ethylpropyl)-3,4-dimethyl-2,6-dinitroaniline

2-[4,5-Dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid

2-(4-Isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-nicotinic acid (salts, esters)

Methyl-3-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]-carbonyl]-amino]-sulfonyl]-2-thiophenecarboxylate (Harmony®)

1-(4,6-Dimethoxypyrimidin-2-yl)-3-(ethylsulfonyl)-2-(pyridylsulfonyl)-urea

2-[-2,4-Dichlorophenoxy]-proionic acid (salts, esters, amides)

5-[2-Chloro-4-(trifluoromethyl)-phenoxy]-2-nitrobenzoic acid (salts)

N-phenyl-N′-1,2,3-thiadiazol-5-ylurea

N-phenyl-N′-1,3,4-thiadiazol-2-ylurea

N-phenyl-N′-2-chloropyrid-3-ylurea

N-3,4-(Dichlorophenyl)-N′,N′-dimethylurea

3-(3-Chloro-4-methoxyphenyl)-1,1-dimethylurea

2-Chloroethylphosphonic acid

S,S.S-Tributyl phosphorotrithioate

S,S,S-Tributyl phosphorotrithioite

2,3-Dihydro-5,6-dimethyl-1,4-dithiin-1,1,4,4-tetraoxide

N-(Phosphonomethyl)-glycines (salts)

Ammonium-DL-homoalanin-4-ylmethylphosphinate

Magnesium chlorate and sodium chlorate

Ammonium sulfate and nitrate

Cyanamides

Potassium iodide

Copper chelates and iron chelates,

Arsenic acid

Hydroxydimethylarsine oxide

1,2-Dihydropyridazine-3,6-dione

7-Oxabicyclo[2,2,1]heptane-2,3-dicarboxylic acid (salts, esters, amides)

6,7-Dihydropyridol (1,2-α:2′,1′-c)pyridilium ion as the dibromide monohydrate salt

1,1′-Dimethyl-4,4′-dipyridinium ion as the dichloride or dimethylsulfate salt

3,5-Dibromo-4-hydroxybenzonitrile

3,5-Diiodo-4-hydroxybenzonitrile

2-Sec-butyl-4,6-dinitrophenol

2-Tert-butyl-4,6-dinitrophenol

2-Sec-amyl-4,6-dinitrophenol

2-Ethylamino-4-isopropylamino-6-methylthio-1,3,5-triazine

1H-1,2,4-Triazol-3-ylamine

2-n-Butylmercaptobenzothiazole

Di-n-butyl-1-n-butylaminocyclohexyl phosphonate

N,N,N-Trimethyl-N-2-chloroethylammonium salts

N,N-Dimethylpiperidinium salts

N-Methylpyridinium salts

α-Cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidinylmethanol

α-Cyclopropyl-α-(4-trifluoromethoxyphenyl)-5-pyrimidinylmethanol

5-(4-Chlorophenyl)-3,4,5,9,10-pentaazatetracyclo[5.4.1.0^(2,6).0^(8,11)]-dodeca-3,9-diones

All-cis-8-(4-chlorophenyl)-3,4,8-triazatetracyclo[4.3.1.0.0^(2,5),0^(7,9)]-dec-3-one

Succinic acid mono-N,N-dimethylhydrazide

Ethyl N,N-dipropylthiolcarbamate

N-2,4-Dimethyl-5-(trifluoromethyl)-sulfonylaminophenylacetamide

1-(4-Chlorophenoxy)-3,3-dimethyl-1-(1,2,4-triazol-1-yl)-2-butanone

2-Propylcarbonyl-5-ethoxycarbonyl-3-hydroxy-2-cyclohexen-1-one

1-(1,2,4-triazol-1-yl)-1-methoxy-2-(2,4-dichlorophenyl)-propan-2-ol

2,2-Dimethyl-4-(1,2,4-triazol-1-yl)-6-phenoxyhexan-3-ol

2,2-Dimethyl-4-(1,2,4-triazol-1-yl)-5-(4-chlorophenyl)-pentan-3-ol

2,2-Dimethyl-4-(1,2,4-triazol-1-yl)-5-(4-chlorophenyl)-pent-4-en-1-ol

2,2-Dimethyl-4-(1,2,4-triazol -1-yl)-5-cyclohexylpent-4-en-3-ol

1-(5-Methyl-1,3-dioxan-5-yl)-4-(1,2,4-triazol-1-yl)-4-(4-trifluoromethylphenyl)-propen-2-ol

Particularly preferred N-phenyl-3,4,5,6-tetrahydroplithalimides are those of the formula I where R is a low molecular weight alkyl radical and A is the group I-1 in which Q is oxygen, R¹ is chlorine or bromine and R² is C₁-C₆-alkyl. The compounds No. 1.1 and in particular No. 1.17 are noteworthy here.

Preferred application rates for these compounds are from 0.02 to 1.0, in particular from 0.05 to 0.5, kg/ha.

Preferred partners for the mixture are listed in the Table below, where the relevant application rates of the partner of the mixture are also stated. The total application rate for the mixture can be determined from the sum of the amount stated for the tetrahydrophthalimides I and the amount stated in each case in the Table.

TABLE Application rate Partner in the mixture kg/ha 3,7-Dichloroquinoline-8-carboxylic acid (salts, esters) (quinclorac) 0.05-0.5 2,4-Dichlorophenoxyacetic acid (salts, esters, amides) 0.05-1   2-[4,5-Dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3- 0.005-0.25 quinolinecarboxylic acid (imazaquin) Methyl 3-[[[[(4-Methoxy-6-methyl-1,3,5-triazin-2-yl)-amino]-carbonyl]- 0.001-0.1  amino-]-sulfonyl]-2-thiophenecarboxylate (Harmony ®) 1-(4,6-Dimethoxypyrimidin-2-yl)-3-(ethylsulfonyl)-2-pyridylsulfonyl)-urea 0.001-0.1  (DPX-E 9636) 5-[2-Chloro-4-(trifluoromethyl)-phenoxy]-2-nitrobenzoic acid (salts) (acifluorfen) 0.1-1  N-Phenyl-N′-1,2,3-thiadiazol-5-ylurea (thidrazuron) 0.01-0.5 (2-Chloroethyl)-phosphonic acid (ethephon) 0.2-4 S,S,S-Tributyl phosphorotrithioate (def) 0.2-2 S,S,S-Tributyl phosphorotrithioite (folex) 0.2-2  Sodium chlorate 0.4-4  7-Oxabicyclo[2,2,1]heptane-2,3-dicarboxylic acid (endothall) 0.2-2  1,1′-Dimethyl-4,4′-bipyridinium ion as the dichloride or dimethylsulfate salt 0.01-1   (paraquat) N,N-Dimethylpiperidinium chloride (mepiquat chloride) 0.05-2   6,7-Dihydropyridol(1,2-α:2′,1′-c)pyridilium dibromide (diquat) 0.1-1  2-Sec-Butyl-4,6-dinitrophenol (dinoseb) 0.5-5 

The Examples which follow describe methods for the preparation of compounds I and II which have been disclosed in earlier applications not yet laid open. The active ingredients stated in the Tables can be obtained by appropriate modification of the starting materials.

PREPARATION EXAMPLES

A) Compounds I in which A=I-2 or I-3

a) 9.9 g of ethane 1,2-dithiol are added to 18.6 g of 2-chloro-5-nitrobenzaldehyde and 0.5 g of p-toluenesulfonic acid in 250 ml of toluene and the mixture is refluxed for 5 hours under a water separator. After the mixture has been cooled, the solvent is removed, the residue is stirred with petroleum ether and the product is filtered off and dried. 25.5 g of 4-chloro-3-(1,3-dithiolan-2-yl)-nitrobenzene (mp. 130-131° C.) are obtained.

b) 24.9 g of the above nitro compound are added a little at a time to a refluxing mixture of 15.9 g of iron powder in 50 ml of methanol and 75 ml of glacial acetic acid, and the mixture is refluxed for 2 hours. After the mixture has been cooled, 250 ml of water are added and the solid is filtered off. The filtrate is extracted with 3 times 100 ml of ethyl acetate, the extracts are dried and evaporated down and the residue is precipitated from petroleum ether, filtered off under suction and dried. 21.5 g of 4-chloro-3-(1,3-dithiolan-2-yl)-aniline (mp. 60-63° C.) are obtained.

c) 11.6 g of the above aniline and 7.6 g of cyclohexene-1,2-dicarboxylic anhydride in 150 ml of glacial acetic acid are stirred for 2 days at room temperature, and the precipitate which separates out is filtered off, washed with water and petroleum ether and dried. 13 g of N-[4-chlorophenyl-3-(1,3-dithiolan-2-yl)]-3,4,5,6-tetrahydrophthalimide (mp. 155-158° C.) are obtained.

Further examples of active ingredients which can be prepared using this principle of synthesis are shown in Tables 2 and 3.

B) Compounds in which A=I-6

N-[4-chloro-3-(4′-methyl-2′-oxo-3′-oxacyclopentylidenemethyl)-phenyl]-3,4,5,6-tetrahydrophthalimide

a) 7.1 g (0.03 mole) of 4-methyl-2-oxo-3-oxacyclopentyl diethylphosphonate [Z. Naturforsch B. 38B (4), 493 (1983] in 8 ml of absolute tetrahydrofuran are added to a mixture of 7.4 g (0.054 mole) of potassium carbonate and 3.5 g (0.0135 mole) of 18-crown-6 in 10 ml of absolute tetrahydrofuran at 0-5° C., while stirring. After about 0.5 h, 5.0 g (0.027 mole) of 2-chloro-5-nitrobenzaldehyde in 6 ml of absolute tetrahydrofuran are added and stirring is continued for 15 h at room temperature. The mixture is worked up by pouring it onto 40 ml of ice water and extracting it several times with ether. The organic phase is washed with 10% strength HCl and H₂O and dried and the solvent is evaporated off, after which the product is separated over silica gel using 9:1 toluene/acetone as an eluant. 1.7 g of 2-(4′-methyl-2′-oxo-3′-oxacyclopentylidenemethyl)-4-nitrochlorobenzene (mp. 87-103° C., isomer mixture) are obtained in this manner.

b) 2.4 g (0.009 mole) of 2-(4′-methyl-2′-oxo-3′-oxacyclopentylidenemethyl)-4-nitrochlorobenzene in 10 ml of glacial acetic acid and 10 ml of methanol are added to a mixture of 3.0 g (0.054 mole) of iron powder, 7.5 ml of glacial acetic acid and 15 ml of methanol in the course of 15 min at 60° C., while stirring. After the end of the addition, the refluxed mixture is stirred for 30 min, cooled to room temperature and filtered, and the solvent is stripped off under reduced pressure. The residue is taken up in ethyl acetate, the solution is washed and dried and the solvent is removed. 2.3 g of crude 4-amino-2-(4′-methyl-2′-oxo-3′-oxacyclopentylidenemethyl) chlorobenzene, which is reacted without further working up, are obtained in this manner.

c) 2.2 g (0.009 mole) of 4-amino-2-(4′-methyl-2′-oxo-3′-oxacyclopentylidenemethyl) -chlorobenzene, 1.4 g (0.009 mole) of 3,4,5,6-tetrahydrophthalic anhydride and 25 ml of glacial acetic acid are refluxed together for 2 while stirring. The mixture is cooled to room temperature, after which the solvent is stripped off, the residue is taken up in 100 ml of ethyl acetate, the solution is washed and dried and the solvent is removed. This procedure gives 3.5 g of crude product, which, after chromatography over silica gel using 98:2 toluene/acetone, gives 2.5 g of N-[4-chloro-3-(4′-methyl-2′-oxo-3′-oxacyclopentylidenmethyl)-phenyl]-3,4,5,6-tetrahydrophthalimide (mp. 98-113° C.).

Further examples of active ingredients which can be prepared using this principle of synthesis are shown in Table 8.

a) 19.4 g of n-butyl 2,3-dihydroxyisobutyrate are added to 18.6 g of 2-chloro-5-nitrobenzaldehyde and 0.5 g of p-toluenesulfonic acid in 250 ml of toluene, and the mixture is refluxed for 5 hours under a water separator. After the mixture has been cooled, the solvent is removed and the residue is dried under greatly reduced pressure. 35 g of 3-(5-methyl-5-n-butoxycarbonyl-1,3-dioxolan-2-yl)-4-chloronitrobenzene (oil) are obtained.

b) 34.4 g of the above nitro compound in 20 ml of methanol are added to a mixture of 16.8 g of iron powder in 30 ml of methanol and 75 ml of glacial acetic acid, the mixture being refluxed for two hours. After the mixture bas been cooled, 250 ml of water are added and the mixture is filtered off under suction. The filtrate is extracted 3 times with 100 ml of ethyl acetate, the extracts are dried and evaporated and the residue is dried under greatly reduced pressure. 31 g of 3-(5-methyl-5-n-butoxycarbonyl-1,3-dioxolan-2-yl)-4-chloroaniline (oil) are obtained.

c) 15.7 g of the above aniline and 7.6 g of cyclohexene-1,2-dicarboxylic anhydride in 150 ml of glacial acetic acid are refluxed for 5 hours. After the mixture has been cooled, 150 ml of water are added, the mixture is extracted with twice 100 ml of methylene chloride and dried and the solvent is removed. The product is purified by chromatography and -dried under greatly reduced pressure. 9.0 g of N-[3-(5-methyl-5-n-butoxycarbonyl-1,3-dioxolan-2-yl)-4-chlorophenyl]-3,4,5,6-tetrahydrophthalimide (oil) are obtained.

Further examples of active ingredients which can be prepared using this principle of synthesis are shown in Table 9.

D) Compounds I in which A=I-8

a) 64.4 g of 2-chlorobenzyl chloride, 76.0 g of ethyl 2-cyanopropionate, 58.0 g of dry potassium carbonate and 0.1 g of 18-crown-6 are refluxed for 3 hours in the absence of moisture. The mixture is filtered off and the residue is distilled to give 69.5 g of ethyl 2-chlorobenzylmethylcyanoacetate (bp.: 107-109° C./0.1)

b) 41.7 ml of concentrated nitric acid (d=1.51) are added to 25.2 g of the ester at from 0° to 5° C. in 30 minutes and the mixture is stirred for a further 30 minutes. The mixture is stirred into 400 ml of ice water and extracted twice with 70 ml of toluene. Washing with 10% strength sodium carbonate solution and water, evaporation of the solvent and recrystallization from 50 ml of diisopropyl ether give 18.9 g of ethyl (2-chloro-5-nitrobenzyl)-methylcyanoacetate (mp.: 714 74° C.).

c) A solution of 18.7 g of nitro compound in 28 ml of methanol and 40 ml of glacial acetic acid is added dropwise to a refluxed mixture of 10.6 g of iron powder in 70 ml of methanol and 15 ml of glacial acetic acid in one hour. The mixture is refluxed for a further 30 minutes and then filtered under suction, and the residue is washed with 50 ml of ethyl acetate. It is stirred into 800 ml of water and extracted with 3 times 100 ml of ethyl acetate. After drying and evaporation of the solvent under reduced pressure, 15.5 g of the ethyl cyanoacetate described above are isolated as a liquid.

This principle of synthesis can be used to prepare, for example, the active ingredients stated in Tables 5 and 6.

E) Compounds I in which A=I-10

13.9 g of N-(4-chloro-3-hydroxyphenyl)-3,4,5,6-tetrahydrophthalimide, 8.2 9 of 3-chloromethyl-5,6-dihydro-2H-thiopyran and 8.3 g of potassium carbonate in 150 ml of acetonitrile are refluxed for hours. The mixture is cooled and filtered, the filtrate is evaporated down, the residue is taken up in 200 ml of methylene chloride and the solution is washed twice with 10% strength sodium hydroxide solution and 3 times with water dried and evaporated out. 15.0 g of N-[4-chloro-3-(3-methoxy-5,6-dihydro-2H-thiopyranyl)-phenyl]-3,4,5,6-tetrahydrophthalimide (mp. 116-119° C.) are obtained.

a) 9.6 g of 1-chloro-4-fluoro-5-nitrophenol, 8.2 g of 3-chloromethyl-5,6-dihydro-2H-thiopyran and 3.8 g of potassium carbonate in 150 ml of acetonitrile are relaxed for 5 hours. After cooling and filtration, the filtrate is evaporated down and the residue is taken up in 200 ml of methylene chloride. The organic phase is washed with 3 times 50 ml of water, dried and evaporated down and the residue is stirred with petroleum ether. 12.5 g of 2-chloro-4-fluoro-5-nitro-(5,6-dihydro-2H-thiopyranyl-3-methoxy)-benzene (mp. 91-94° C.) are obtained.

b) 12.2 g of the above nitro compound are added a little at a time to a reflux mixture of 6.7 g of iron powder in 50 ml of methanol and 7.5 ml of glacial acetic acid and refluxing is continued for a further 2 hours. The mixture is cooled, after which 250 ml of water are added and the mixture is filtered off under suction. The filtrate is extracted with 3 times 100 ml of ethyl acetate, the extracts are dried and the solvent is evaporated under reduced pressure. Purification by chromatography gives 5.5 g of 4-chloro-2-fluoro-5-(5,6-dihydro-2-H-thiopyranyl-3-methoxy)-aniline (mp. 73-74° C.).

c) 5.5 g of the above aniline and 3.0 g of cyclohexene-1,2-dicarboxylic anhydride in 100 ml of glacial acetic acid are refluxed for 5 hours. The mixture is cooled, after which 50 ml of water are added and filtration is carried out. The precipitate is washed with water and dried. 6.0 g of N-(4-chloro-2-fluoro-5-(5,6-dihydro-2H-thiopyranyl-3-methoxy)-phenyl]-3,4,5,6-tetrahydrophthalimide (mp. 134-137° C.) are obtained.

Further examples of active ingredients which can be prepared using these principles of synthesis are shown in Table 4.

F) Compounds II

a) 4.9 g (0.03 mole) of 6-amino-3,4-dihydro-2H-1,4-benzoxazin-3-one in 50 ml of dimethy1formamide are initially taken, 0.79 g (0.033 mole) of sodium hydride is added at 5° C. and the mixture is stirred for 30 minutes at this temperature. Thereafter, 5.9 g (0.033 mole) of 3-bromomethyltetrahydropyran are added, stirring is continued for 3 hours at 60° C., 200 ml of water are added the mixture is extracted twice with 200 ml of methylene chloride, the extracts are dried and the solvent is evaporated under reduced pressure. 5 g (64%) of 4-(tetrahydropyran-4- ylmethyl)-6-amino-3,4-dihydro-2H-1,4-benzoxazin-3-one (oil) are obtained.

b) 4.5 g (0.017 mole) of the above aniline and 2.7 g (0.018 mole) of cyclohexene-1,2-dicarboxylic anhydride in 70 ml of glacial acetic acid are stirred for 3 hours at 70° C. After the mixture has been cooled, 100 ml of water are added, and the precipitate is filtered off, washed with water and dried. 3.5 g (52%) of N-[4-tetrahydropyran-4-ylmethyl)-3,3-dihydro-2H-1,4-benzoxazin -3-on-6-yl]-3,4,5,6-tetrahydrophthalimide (mp. 187-189° C.),are obtained.

The active ingredients shown in Tables 10 to 12 can be prepared using this principle of synthesis. Examples of active ingredients of the formulae I and II are shown in Tables 1 to 16 below.

G) Compounds I in which A=I-1 and Q=0

are obtained by a Wittig reaction of

with a phosphorane

N-[5-(1′-methoxycarbonyl-1′-bromoethenyl)-4-chloro-2-fluorophenyl]-3,4,5,6-tetrahydrophthalimide

4.60 g (15 millimoles) of N-(2-fluoro-4-chloro-5-formylphenyl)-3,4,5,6-tetrahydrophthalimide and 6.80 g (16.5 millimoles) of carbomethoxybromomethylenetriphenylphosphorane in 15 ml of methanol are stirred at room temperature for 15 minutes. The reaction mixture is cooled to 0° C. and the precipitated product is filtered off.

Yield: 70%, mp.: 155-157° C.

N-[5-(1′-ethoxycarbonyl-1′-chloroethenyl)-4-chloro-2-fluorophenyl]-3,4,5,6-tetrahydrophthalimide

4.60 g (15 millimoles) of N-(2-fluoro-4-chloro-5-for-mylphenyl)-3,4,5,6-tetrahydrophthalimide and 6.30 g (16.5 millimoles) of carboethoxychloromethylenetriphenylphosphorane in 15 ml of ethanol are stirred at room temperature for 15 minutes. The mixture is then cooled to 0° C. and the precipitated product is filtered off.

Yield: 68%, mp.: 104-107° C.

N-[3-(1′-ethoxycarbonyl-1′-chloroethenyl)-4-chlorophenyl]-3,4,5,6-tetrahydrophthalimide

651 g (2.25 moles) of N-(4-chloro-5-formylphenyl)-3,4,5,6-tetrahydrophthalimide are introduced a little at a time into 956 g (2.5 moles) of carboethoxychloromethylenetriphenylphosphorane in 1.3 l of ethanol at 30° C. After the end of the addition, stirring is carried out for a further 30 minutes. The mixture is then cooled to −10° C. and the precipitated product (3) is filtered off.

Yield: 82%, mp.: 112-114° C.

TABLE 1a Compounds I in which A = I-1 and Q = O

Com- Phys. pound data No. R R¹ R² Configuration mp. (° C.) 1.1 H Br CH₃ 94-95 1.2 H Br CH₃ Z 93-95 1.3 H Br CH₃ E 143-144 1.4 H Br C₂H₅ 91-92 1.5 H Br n-C₃H₇ 78-80 1.6 H Br n-C₃H₇ Z:E = 45:55 72-73 1.7 H Br i-C₃H₇ 119-121 1.8 H Br n-C₄H₉ 73-74 1.9 H Br n-C₄H₉ Z:E = 50:50 Oil 1.10 F Br CH₃ Z:E = 90:10 121-123 1.11 F Br CH₃ E 102-103 1.12 F Br C₂H₅ Z 105-110 1.13 F Br n-C₄H₉ 55-60 1.14 F Br n-C₆H₁₃ Oil 1.15 H Br (CH₂)₂OCH₃ 136-137 1.16 H Cl CH₃ 138-140 1.17 H Cl C₂H₅ 87-89 1.18 H Cl n-C₃H₇ 83-85 1.19 H Cl i-C₃H₇ 140-141 1.20 H Cl n-C₄H₉ 90-91 1.21 H Cl n-C₅H₁₁ 112-114 1.22 H Cl (CH₂)₂CH(CH₂)₂ 68-70 1.23 H Cl (CH₂)₂OCH₃ 128-130 1.24 H Cl (CH₂)₂OC₂H₅ 58-60 1.25 H Cl (CH₂)₂O-n-C₄H₉ Oil 1.26 H CH₃ CH₃ 132-134 1.27 H CH₃ CH₃ Z:E = 50:50 1.28 H CH₃ C₂H₅ 62-63 1.29 H CH₃ n-C₃H₇ 79-80 1.30 H CH₃ i-C₃H₇ 74-75 1.31 H CH₃ n-C₄H₉ 84-86 1.32 H CH₃ i-C₄H₉ 86-88 1.33 H CH₃ n-C₅H₁₁ 47-49 1.34 H CH₃ i-C₅H₁₁ 64-65 1.35 H CH₃ Benzyl 75-78 1.36 H CH₃ 2-Phenylethyl Oil 1.37 H CH₃ 1-Phenyl-prop-2-yl 108-109 1.38 H CH₃ Propargyl 151-152 1.39 H CH₃ CH₂CH═C(CH₃)₂ 49-51 1.40 H CH₃

Oil 1.41 H CH₃ (CH₂)₂OCH₃ 41-44 1.42 H CH₃ (CH₂)₂OC₂H₅ 39-43 1.43 H CH₃ (CH₂)₂O_(n)—C₄H₉ Oil 1.44 H CH₃

45-47 1.45 H CH₃

89-80 1.46 H CH₃

Oil 1.47 H CH₃

55-56 1.48 H CH₃ (CH₂)₂SC₂H₅ 39-40 1.49 H CH₃ (CH₂)₂S-i-C₃H₇ 67-68 1.50 H CH₃ H 212-213 1.51 H C₂H₅ CH₃ 103-104 1.52 H C₂H₅ C₂H₅ 49-50 1.53 H C₂H₅ n-C₃H₇ 47-48 1.54 H C₂H₅ n-C₄H₉ Oil 1.55 H C₂H₅ (CH₂)₂OCH₃ 46-48 1.56 H C₂H₅

32-33 1.57 H n-C₃H₇ CH₃ Oil 1.58 H n-C₃H₇ (CH₂)₂OCH₃ Oil 1.59 H n-C₅H₁₁ CH₃ Oil 1.60 H n-C₅H₁₁ (CH₂)₂OCH₃ Oil 1.61 F CH₃ CH₃ Z:E = 30:70 Oil 1.62 F CH₃ C₂H₅ E 96-97 1.63 H CN CH₃ 154-155 1.64 H CN C₂H₅ 140-142 1.65 H CN i-C₃H₇ 132-133 1.66 H CN i-C₄H₉ 134-135 1.67 H CN CH₂C₆H₅ 182-183 1.68 H CN (CH₂)₂OCH₃ 114-116 1.69 H CN (CH₂)₂O-i-C₃H₇ 63-65 1.70 H CN

120-123 1.71 H CN

56-57 1.72 H CN H 148-151 1.73 F H CH₃ — 1.74 F H C₂H₅ 133-135 1.75 F CH₃ C₂H₅ Oil

TABLE 1b Compounds I in which A = I-1. Q = S and R = H

Compound No. R¹ R² mp. (° C.) 1.76 CH₃ CH₃ 135-136 1.77 CH₃ C₂H₅ 105-106 1.78 CH₃ n-C₃H₇ 80-82 1.79 CH₃ n-C₄H₉ 75-77 1.80 CH₃ i-C₄H₉ 86-87 1.81 CH₃ CH₂CH₂OH 77-79 1.82 Br CH₃ Oil 1.83 Br C₂H₅ Oil 1.84 Br n-C₃H₇ Oil 1.85 Br i-C₃H₇ Oil 1.86 Br CH₂CH₂OH 70-72 1.87 Br CH₂CH₂OCH₃ Oil

TABLE 1c Compounds I in which A = I-1. Q = NR⁸ and R = H

Com- pound mp. No. R¹ R² R⁸ (° C.) 1.88 CH₃ 3-Methyl-butyl-2 H 122-123 1.89 CH₃ Neopentyl H 123-124 1.90 CH₃ Isoamyl H 88-89 1.91 CH₃ 2-Ethylbutyl H 117-118 1.92 CH₃ n-Pentyl H 87-88 1.93 CH₃ 2-Methylpentyl H 68-69 1.94 CH₃ Allyl H 89-90 1.95 CH₃ 2-Methylallyl H 70-71 1.96 C₂H₅ Allyl H 117-118 1.97 CH₃ 2-Methoxyethyl H  99-100 1.98 CH₃ 2-Methyl-thioethyl H Oil 1.99 CH₃ 3-Methoxypropyl-2 H 70-71 1.100 CH₃ 1-Methoxybutyl-2 H 98-99 1.101 CH₃ 4-Methoxybutyl-2 H Oil 1.102 CH₃ CH₂CH₂OCH₃ CH₂CH₂OCH₃ 59-61 1.103 CH₃ Ethoxy H 83-84 1.104 CH₃ Allyloxy H 120-121 1.105 CH₃ Methoxy Ch₃  99-101 1.106 C₂H₅ Phenyl H 179-180 1.107 CH₃ 2-Cl-phenyl H 159-160 1.108 CH₃ 3-Cl-phenyl H 176-178 1.109 CH₃ 4-Cl-phenyl H 128-130 1.110 CH₃ 2-CH₃-phenyl H 104-105 1.111 CH₃ 3-CH₃-phenyl H 172-173 1.112 CH₃ 2-CH₃O-phenyl H 204-205 1.113 CH₃ 2-Cl,6-CH₃-phenyl H 167-168 1.114 CH₃ 2-6-Cl,Cl-phenyl H 186-187 1.115 Br n-Hexyl CH₃ Oil

TABLE 2 Compounds I in which A = I-2

Compound Physic. data No. R X R³ mp. (° C.) 2.1 H O H 141-142 2.2 H O CH₃ Oil 2.3 F O CH₃ Oil 2.4 H O CH₂OH 91-93 2.5 H S CH₃ 101-102 2.6 H S CH₂OH 88-90 2.7 H S CH₂Cl 109-110 2.8 H S CH₂CN 82-84 2.9 H S

80-81 2.10 H S CH₂SH 96-97 2.11 H S CH₂SCH₃ Oil 2.12 H S

Oil 2.13 H S H 155-158 2.14 F S H 160-161 2.15 F S CH₃ 138-139

TABLE 3 Compounds I in which A = I-3

Compound Physic. data No. R A mp. (° C.) 3.1 H

198-200 3.2 H

152-159 3.3 H

134-135

TABLE 4 Compounds I with A = I-10

Compound Physic. data No. R R¹⁴ mp. (° C.) 4.1 F

104-106 4.2 H

108-110 4.3 H

90-92 4.4 F

131-133 4.5 H

140-141 4.6 H

74-76 4.7 H

143-146 4.8 F

162-164 4.9 H

116-119 4.10 F

134-137 4.11 H CH₂CH═CH₂ 74-75 4.12 H CH₂C≡CH 189-190 4.13 Cl CH₂C≡CH 141-143 4.14 F CH₂C≡CH 134-136 4.15 F

4.16 H

110-112

TABLE 5 Compounds I in which A = I-8

Compound Physic. data No. R R² R⁹ R¹⁰ mp. (° C.) 5.1 H C₂H₅ H H Oil 5.2 H CH₃ Br H 102-106 5.3 H CH₃ CH₃ H Oil 5.4 H CH₃ C₂H₅ H Oil 5.5 H CH₃ CN H Oil 5.6 H C₂H₅ CN H Oil 5.7 H CH₃ CH₃ CH₃ 103-104 5.8 Cl CH₃ CH₃ CH₃ 122-123 5.9 F CH₃ CH₃ CH₃ 68-70 5.10 Cl C₂H₅ CH₃ CH₃ 88-89 5.11 F C₂H₅ CH₃ CH₃ Oil 5.12 Cl i-C₅H₁₁ CH₃ CH₃ 112 5.13 F i-C₅H₁₁ CH₃ CH₃ 98-99 5.14 H (CH₂)₂OCH₃ CH₃ CH₃ Oil 5.15 Cl (CH₂)₂OCH₃ CH₃ CH₃ Oil 5.16 F (CH₂)₂OCH₃ CH₃ CH₃ Oil 5.17 Cl (CH₂)₂OC₂H₅ CH₃ CH₃ Oil 5.18 F (CH₂)₂OC₂H₅ CH₃ CH₃ 63-64 5.19 F CH₃ CH₃ C₂H₅ Oil 5.20 F CH₃ C₂H₅ C₂H₅ Oil 5.21 H CH₃ CH₃

108-110 5.22 F CH₃ CH₃

Oil 5.23 H C₂H₅ CH₃

103-104 5.24 F C₂H₅ CH₃

Oil 5.25 H C₂H₅ C₂H₅

Oil 5.26 F C₂H₅ C₂H₅

Oil 5.27 F CH₃ n-C₄H₉

84-96 5.28 H CH₃ n-C₄H₉

117-119 5.29 H CH₃ CH₃

120-122 5.30 F CH₃ CH₃

Oil 5.31 H C₂H₅ Cl

123-125 5.32 H CH₃ C₂H₅ C₂H₅ 103-105 5.33 H CH₃ CN n-C₄H₉ 113-114 5.34 F CH₃ CN n-C₄H₉ 124-125 5.35 H C₂H₅ CN CH₃ 111-113 5.36 F C₂H₅ CN CH₃ Oil 5.37 H C₂H₅ CN C₂H₅ 124-126 5.38 F C₂H₅ CN C₂H₅ 87-89 5.39 H CH₃ —(CH₂)₄— 108-109 5.40 F CH₃ —(CH₂)₄— 65-70 5.41 F CH₃ —(CH₃)₄— 131-134 5.42 H CH₃

Oil 5.43 F CH₃

Oil 3.44 H C₂H₅

Oil 5.45 F C₂H₅

Oil 5.46 H C₂H₅

138-140

TABLE 6 Compound I in which A = I-8

Compound Physic. data No. R R² R⁹ mp. (° C.) 6.1 H CH₃ H 102-105 6.2 H C₂H₅ H oil 6.3 F C₂H₅ H 89-91 6.4 H CH₃ Cl 131-133 6.5 F CH₃ Cl 122-125 6.6 H CH₃ CH₃  99-110 6.7 H CH₃ n-C₃H₇  99-110 6.8 H CH₃ n-C₄H₉  99-101 6.9 H CH₃ CH₂—CH═CH₂ 108-110 6.10 H CH₃ CH₂C≡CH 133-135 6.11 H CH₃ CH₂CH₂CH═CH₂ 100-102 6.12 H CH₃ CH₂CH═CHCH₃ 90-93 6.13 H CH₃ CH₂CH₂OCH₃ >250 6.14 H CH₃ CH₂CH₂OC₂H₅ oil 6.15 H CH₃ CH₂SCH₃ 130-133 6.16 H CH₃

oil

TABLE 7a Compounds I in which A = I-9 and

or R¹¹ = CH₂(CH₃)₂COOR² in the case of 7.29 R¹¹ = CH₂C(CH₃)₂COOR² in the case of 7.29 Compound Physic. data No. R R² R⁴ R¹² mp. (° C.) 7.1  H H H H 178-182 7.2  H CH₃ H H oil 7.3  H C₂H₅ H H 116-117 7.4  H CH₂CH═CH₂ H H 83-86 7.5  H n-C₄H₉ H H 91-92 7.6  H n-C₆H₁₃ H H 64-66 7.7  H (CH₂)₃OC₂H₅ H H oil 7.8  H CH₃ C₂H₅ H oil 7.9  H C₂H₅ C₂H₅ H oil 7.10 H CH₃ CH₃ H viscous mass 7.11 H n-C₂H₅ CH₃ H 85-87 7.12 H n-C₃H₇ CH₃ H viscous mass 7.13 H CH₂CH═CH₂ CH₃ H viscous mass 7.14 H CH₂C≡CH CH₃ H oil 7.15 H i-C₄H₉ CH₃ H oil 7.16 H n-C₅H₁₁ CH₃ H oil 7.17 H n-C₈H₁₇ CH₃ H oil 7.18 H

CH₃ H oil 7.19 i i-C₄H₉ CH₃ H oil 7.20 H CH₂CH₂OCH₃ CH₃ H oil 7.21 H CH₂CH₂OC₂H₅ CH₃ H oil 7.22 H CH₂C₆H₅ CH₃ H oil 7.23 7.24 H CH₃ H CN Oil 7.25 Cl CH₃ H CN 108-110  7.25a H C₂H₅ H CN viscous mass 7.26 Cl C₂H₅ H CN Oil 7.27 H CH₃ CH₃ CN viscous mass 7.28 Cl CH₃ CH₃ CN 133-138 7.29 H CH₃ — H Oil

TABLE 7b Compounds in which A = I-9

Compound Physic. data No. R R¹¹ R¹² mp. (° C.) 7.30 H CH₃ H 139-141 7.31 H C₂H₅ H 97-98 7.32 Cl C₂H₅ H 143-146 7.33 H n-C₃H₇ H 86-87 7.34 H CH₂CH═CH₂ H 76-78 7.35 H CH₂CH═CH₂ CN viscous mass 7.36 Cl CH₃ CN Oil

TABLE 8 Compounds I in which A = I-6

Compound Physic. data No. R R⁴ mp. (° C.) 8.1 O H H 176-180 8.2 O H CH₃  98-113 8.3 O F H  89-118

TABLE 9 Compounds I in which A = I-7

Compound Physic. data No. R R⁸ R⁴ R⁵ mp. (° C.) 9.1 H CH₃ CH₃ H Oil 9.2 H CH₃ C₂H₅ H Oil 9.3 H CH₃ H CH₃ Oil 9.4 H C₂H₅ CH₃ H Oil 9.5 F C₂H₅ CH₃ H Oil 9.6 H C₂H₅ C₂H₅ H Oil 9.7 F C₂H₅ C₂H₅ H Oil 9.8 H n-C₃H₇ CH₃ H Oil 9.9 F n-C₃H₇ CH₃ H Oil 9.10 H n-C₃H₇ C₂H₅ H Oil 9.11 F n-C₃H₇ C₂H₅ H Oil 9.12 H i-C₃H₇ H CH₃ Oil 9.13 H n-C₄H₉ CH₃ H Oil 9.14 F n-C₄H₉ CH₃ H Oil 9.15 H n-C₄H₉ C₂H₅ H Oil 9.16 F n-C₄H₉ C₂H₅ H Oil 9.17 H n-C₄H₉ H CH₃ Oil 9.18 H i-C₄H₉ CH₃ H Oil 9.19 H 2-Ethylhexyl C₂H₅ H Oil

TABLE 10 Compounds II in which n = 0 and Y = S, O or CH₂

Compound Physic data No R R¹⁶ Y mp (° C.) 10.1 F

S 187-189 10.2 H H CH₂ 237-238 10.3 H

CH₂ 150-152 10.4 H CH₂C≡CH O 190-192

TABLE 11 Compounds II in which E and Y = CH₂

Compound Physic. data No. R R¹⁶ mp (° C.) 11.1 H H 237-238 11.2 H CH₃ 232-234 11.3 H CH₂CH═CH₂ 168-170 11.4 H CH₂C≡CH 196-198 11.5 H CH₂C₆H₅ 173-175 11.6 H

188-190 11.7 H

147-149

TABLE 12 Compounds II in which E = O and Y CHR⁴

Compound Physic. data. No. R R¹⁶ R⁴ mp. (° C.) 12.1 H

H 127-129 12.2 H

H 145-147 12.3 H

H 138-140 12.4 H

CH₃ 145-147 12.5 F

H 12.6 F

H 178-179 12.7 H

H 140-142 12.8 H

H 165-166 12.9 F

H 204-206 12.10 H

H 187-189 12.11 H

CH₃ 150-152 12.12 H

H 178-180 12.13 H

H 157-158 12.14 H

H 177-178 12.15 H H H 242-243 12.16 H CH₂CH═CH H 168-170 12.17 H CH₂C≡CH H 206-208 12.18 H CH₂C≡CH CH₃ 206-208

TABLE 13 Compounds I in which A = I-4

Compound Physic. data No. R R⁷ R⁴ R⁵ mp. (° C.) 13.1 H CH₃ H H 127-130 13.2 H C₂H₅ H CH₃ 123-125 13.3 H CH₃ CH₃ H 160-162 13.4 H CH₃ CH₃ CH₃ 105-107

TABLE 14 Compounds 1 in which A = I-5

Compound Physic. data No. R R⁴ R⁷ R¹³ mp. (° C.) 14.1 H H CH₃

Oil 14.2 H CH₃ CH₃ H Oil 14.3 H CH₃ CH₃

84-86

TABLE 15 Compounds I in which A = I-11

Compound Physic daia No. R R¹⁵ mp (° C.) 15.1 H H 231-233 15.2 H CH₂C≡CH 140-142 15.3 Cl N═C(CH₃)2 147-148 15.4 H

Oil 15.5 H

97-99 15.6 H

83-85

TABLE 16 Compounds I in which A = H or cyanoalkyl

Compound Physic data No. R A mp. (° C.) 16.1 H H 161-162 16.2 H CH₂CH₂CN 88-90

Examples of use

The comparative agents used were

I. N-phenyl-N′-(1,2,3-thiadiazol-5-yl)-urea and

II. 6,7-dihydropyridol(1,2-α:2′,1′-c)pyridilium as the dibromide monohydrate salt

and the compounds III-VI from EP-A 207 894, which compounds are stated under Example C

EXAMPLE A

Young cotton plants (Delta Pine variety, development stage: 5-6 developed foliage leaves) were cultivated under greenhouse conditions (day/night temperature 23/16° C., relative humidity 50-70%) and the foliage was treated, until dripping wet, with aqueous formulations of the stated active ingredients. The converted amount of water was 1,000 l/ha. 12 days after application of the active ingredient, the number of dropped leaves and the degree of defoliation as a percentage of the control were stated. No dropping of leaves occurred in the untreated control plants.

Converted Agent containing application rate % active ingredient No. kg/ha defoliation 1.1 0.062 26 0.125 61 0.250 80  1.26 0.062 67 0.125 79 0.250 89  1.17 0.062 55 0.125 84 0.250 89 2.5 0.062 50 0.125 70 0.250 97 4.1 0.062 83 Comparative agent I 0.062 13 0.125 31 0.250 67 Comparative agent II 0.250 11 0.500 27

The results from Example A show that the novel agents are clearly superior to the commercial active ingredients I and II and display their good action as defoliants even at relatively low temperatures.

EXAMPLE B

Young sunflower plants (Spanners Allzweck variety, stage of development: 3 developed foliage leaves) were cultivated under greenhouse conditions and the foliage was treated, until dripping wet, with aqueous formulations of the stated active ingredients. The converted amount of water was 1,000 l/ha. 3 days after application of the active ingredient, the degree of withering of the leaves (desiccation) was rated.

Converted Agent containing application rate Withering of active ingredient No. kg/ha leaves 2.5 0.25 +/++ 0.50 ++ 1.00 ++/+++ Comparative agent II 0.25 +/++ 0.50 ++ 1.00 +++

The results described show that the novel agent leads to withering (desiccation) of the leaves in sunflowers in a similar manner to the commercial agent II.

EXAMPLE C

Young cotton plants (Delta Pine variety, stage of development: 5-6 developed foliage leaves) were cultivated under green house conditions (day/night temperature 28/20° C., relative humidity 514 70%) and the foliage was treated, until dripping wet, with aqueous formulations of the stated active ingredients. The converted amount of water was 1,000 l/ha. 3 days after application of the active ingredient, the number of dropped leaves and the degree of defoliation as a percentage of the control were stared. No dropping of leaves occurred in the untreated control plants.

Agent containing Converted % active ingredient No. application rate kg/ha defoliation 1.1 0.125 100 0.250 98 1.17 0.125 95 0.250 100 2.5 0.125 97 0.250 100 7.27 0.125 100 0.250 95 Comparative agents III-VI from EP-207 894

0.125 0.250 74 78

0.125 0.250 48 53

0.125 0.250 34 58

0.125 0.250 42 77

The results show that the novel agents are clearly superior to the comparative agents from EP-A-207 894, which are stated subsequently, and display their good action as defoliants at much lower application rates. 

We claim:
 1. A method for the dessication and abscission of plant organs, wherein an effective plant organ desiccating and abscising amount of a derivative of N-phenyl-3,4,5,6-tetrahydrophthalimide of the formula I

where R is hydrogen, fluorine or chlorine, A is group I-1, I-2 or I-3

wherein R¹ is hydrogen, chlorine, bromine, cyano or C₁-C₆alkyl, R² is hydrogen, C₁-C₈-alkyl, C₁-C₈-alkenyl C₂-C₈-alkenyl, C₂-C₄-alkynyl, C₁-C₄-alkoxy-C₁-C₄-alkyl, C₁-C₄-alkylthio-C₁-C₄-alkyl, or phenyl-C₁-C₃-alkyl or phenyl which is unsubstituted or substituted by halogen , R⁴ and R⁵ are each hydrogen or C₁-C₃-alkyl, Q is oxygen or sulfur, R⁷ is hydrogen, C₁-C₆-alkyl, C₁-C₆-alkoxyalkyl, C₁-C₆-alkylthioalkyl or C₅ or C₆-cycloalkyl, and R¹³ is hydrogen or C₁-C4-alkoxycarbonyl, is applied to plants or their habitat.
 2. A method as claimed in claim 1, wherein an N-phenyl-3,4,5,6-tetrahydrophthalimide of the formula I, where R is hydrogen and A is a group I-1

is applied.
 3. A method as claimed in claim 1, wherein an N-phenyl-3,4,5,6-tetrahydrophthalimide of the formula I where R is hydrogen, A is a group I-1, Q is oxygen, R¹ is chlorine or bromine and R² is methyl or ethyl, is applied.
 4. A method as claimed in claim 1, wherein from 0.001 to 5 kg/ha of the N-phenyl-3,4,5,6-tetrahydrophthalimide of the formula I as set forth in claim 1 is applied to plants or their habitat.
 5. The method of claim 3 wherein R¹ is chlorine and R ² is C ₂ H ₅. 